New types of integrated circuits are continually being developed. Some of the newer integrated circuit devices have an increased number of functions and operate at higher speeds than older types of integrated circuits. The newer types of integrated circuits often produce more heat and operate at higher device temperatures than older types of integrated circuits.
The semiconductor industry has been developing newer types of integrated circuit packages for providing efficient and cost effective heat removal for such integrated circuits. The design goal is to make plastic integrated circuit packages that are smaller, thinner, cooler, cheaper, and easy and quick to manufacture.
One of the newer types of integrated circuit package is a leadless package family that is referred to as QFN. The letters QFN stand for Quad, Flat, Non-leaded. QFN integrated circuit packages are plastic semiconductor packages with metal terminals located on the bottom of the package body along the periphery of the package body. The terminals are essentially flush with the bottom of the surface of the plastic package body. For this reason, QFN packages are categorized as “flat” and “non-leaded.”
QFN packages have terminals on all four sides of the bottom of the package. For this reasons, QFN packages are categorized as “Quad” packages. QFN packages can have either a square body or a rectangular body. QFN packages can have either symmetric or non-symmetric terminal patterns.
When QFN packages are attached to an underlying printed circuit board, solder is applied to a leadframe that forms the bottom of the QFN package. Solder is also applied to each of the metal terminals on the periphery of the QFN package. A solder joint is formed between the QFN package and the printed circuit board to attach the leadframe and the terminals of the QFN package and the printed circuit board.
The solder joint between the printed circuit board and the QFN integrated circuit package may be subjected to physical or thermal stresses. If the stress on the solder joint reaches sufficiently high levels then the solder joint may crack and the solder material may delaminate. This may cause the QFN integrated circuit package to become electrically (and even physically) disconnected from the underlying printed circuit board.
There is therefore a need in the art for an improved system and method for providing a strong solder joint between a QFN integrated circuit package and a printed circuit board. There is generally a need in the art for an improved system and method for increasing the solder joint reliability in a QFN integrated circuit package.